The entire disclosure of the Priority document, Japanese Patent Application No. 2000-93576, filed Mar. 30, 2000, is hereby incorporated by reference herein its entirety.
1. Field of Invention
The present invention relates to display devices. Particularly, the invention relates to an organic electro luminescent display (OELD) or liquid crystal display (LCD).
2. Description of Related Art
Recently, the number of display devices using liquid crystal (hereinafter, referred to as display) is increasing at a rapid rate. Displays of this type are low in power consumption and are small, relative to a CRT display. Accordingly, it is important to take advantage of the merits of such a display, and produce a display that exhibits low power consumption and improved space saving.
Display devices of this type include those that effect the display by the use of current-driven luminescent devices instead of liquid crystal. Unlike a liquid crystal display, this current-driven luminescent device is a spontaneous luminescent device that emits light when supplied with current. This current-driven luminescent device can achieve high definition display. Moreover, no backlight is required, thereby achieving power reduction, increased viewing angle, increased constant ratio and so on. Among such current-driven luminescent devices, the EL devices (ElectroLuminescent devices) can be formed on a large-sized glass substrate. They are suited for displays, because thickness reduction and area increase, capacity increase (dot-matrix precision increase) and full color can be achieved.
One drawback of the EL devices is that when thin film transistors are used for driving pixels, for example, it is difficult to obtain accurate tonal levels due to variation in electric characteristic of the thin film transistors.
Therefore, it is one object of the present invention to provide a display device capable of accurately representing tonal levels. Furthermore, another object is to provide a display device capable of achieving space saving and power reduction for the system overall.
A display device according to the present invention includes storage circuits for storing image signals as binary data signals by driving connected write and data lines of a plurality of write lines and a plurality of data lines correspondingly disposed in an array pattern having a dot as a minimum unit of display. The display device also includes current-driven luminescent elements for emitting light depending on an amount of current supplied, display control sections connected between the storage circuit and the current-driven luminescent element to supply an amount of current depending on an electric power supplied on the basis of a value of the image signals stored in the storage circuits and control light emission of the current-driven luminescent elements connected, provided, as sets, with n sets in the same form in order for 2n tonal levels of representation within the dot array pattern to supply to each of the n sets an electric power in accordance with a place value represented by the image signals stored in the storage circuits.
In the display device according to the present invention, in order to represent tonal levels of 2n, there are provided within the dot array pattern n sets in the same form of storage circuits for storing image signals as binary data signals due to driving the connected write and data lines of a plurality of write lines and a plurality of data lines laid correspondingly to the dot array pattern as a minimum unit of display. Further, there are provided liquid crystal drive sections for driving a liquid crystal depending on a voltage supplied and display control section for effecting tonal control using the liquid crystal by the supply of supplied voltage to the liquid crystal drive sections on the basis of a value of the image signals stored in the storage circuits, thereby supplying, to each set, power depending on a place value represented by the image signals stored by the storage circuits.
A display device according to the present invention includes storage circuits for storing image signals as binary data signals by driving the connected write and data lines of a plurality of write lines and a plurality of data lines correspondingly disposed in an array pattern having a dot as a minimum unit of display. The display device further includes current-driven luminescent elements for emitting light depending on an amount of current supplied, display control sections connected between the storage circuit and the current-driven luminescent element, to supply an amount of current depending on an electric power supplied on the basis of a value of the image signals stored in the storage circuits and control light emission of the current-driven luminescent elements connected, provided, as sets, with n sets in the same form in order for 2n tonal levels of representation within the dot array pattern to supply to each of the n sets an electric power in accordance with a place value represented by the image signals stored in the storage circuits.
In this display device, a plurality of write lines and a plurality of data lines are laid correspondingly in an array pattern having a dot as a minimum unit of display. Within the dot array pattern are provided n sets of storage circuits storing image signals due to driving the connected write and data lines, current-driven luminescent elements for emitting light depending on an amount of current supplied, and display control sections for supplying an electric current in an amount dependent upon an electric power supplied to the current-driven luminescent elements. The sets are given the same form in respect of cost, occupation area and so on. Each set is adjusted in brightness by the supply of an electric power depending on a place value represented by the image signals stored in the storage circuits.
Also, a display device according to the invention configures each of the current-driven luminescent elements by an EL element. In this display device, display is made by EL elements as one kind of current-driven luminescent elements having the features of reduced thickness, high definition and low power consumption.
Also, a display device according to the invention includes storage circuits for storing image signals as binary data signals by driving connected write and data lines of a plurality of write lines and a plurality of data lines laid correspondingly to an array pattern of a dot as a minimum unit of display, liquid crystal drive sections for driving a liquid crystal depending on a voltage supplied, and display control sections connected for supplying a supplied voltage to the liquid crystal drive sections on the basis of the image signals stored in the storage circuits thereby effecting tonal control using the liquid crystal, provided, as sets, with n sets in the same form in order for 2n tonal levels of representation within the dot array pattern to supply to each of the n sets an electric power in accordance with a place value represented by the image signals stored in the storage circuits.
In this display device, a plurality of write lines and a plurality of data lines are correspondingly disposed in an array pattern having a dot as a minimum unit of display. Within the dot array pattern are provided n sets of storage circuits storing image signals due to driving the connected write and data lines, liquid crystal driving sections for driving the liquid crystal depending on a voltage supplied, and display control sections for supplying an electric voltage to the liquid crystal driving sections. The sets are given the same form in respect of cost, occupation area and so on. Each set is adjusted in brightness by the supply of an electric power depending on a place value represented by the image signals stored in the storage circuits.
Also, a display device according to the invention forms each of the storage circuits and each of the display control sections by polycrystalline silicon TFTs.
In this display device, a transparent insulating substrate can be used. By forming the storage circuits and display control sections on inexpensive polycrystalline silicon TFTs, the light emitted by the EL elements is taken out by through the substrate.
Also, a display device according to the invention includes a display drive section laid with a plurality of write lines, a plurality of data lines and power supply lines correspondingly disposed in an array pattern having a dot as a minimum unit of display, and having storage circuits for storing image signals when write signals are transmitted through the write lines and image signals are transmitted through the data lines and display control sections for supplying an electric current based on an electric power supplied through the power supply lines to the current-driven luminescent elements on the basis of the image signals, provided, as sets, with n sets in the same form in order for 2n tonal representation within the dot array patterns. The invention further includes a row decoder section for selecting rows to transmit write signals to the write lines, a word line driver section for supplying an electric power for the storage circuits to hold storage and transmitting write signals to the write lines selected by the row decoder section, a column decoder for selecting the data lines, and a column selecting switch section for transmitting image signals as data signals for controlling display onto the data lines selected by the column decoder section, all of which can be integrated and integrally formed on a semiconductor or insulating substrate.
In this display device, there are provided a plurality of write lines and a plurality of data lines laid correspondingly to an array pattern having a dot as a minimum unit of display to provide, within the dot array pattern, n sets of storage circuits for storing image signals due to driving the write and data lines connected and display control sections for supplying an amount of current dependent on an electric power supplied to the current-driven luminescent elements. The display device further including display drive section provided within the dot array pattern, a row decoder section for selecting a row for transmitting a write signal to the write line, a word line driver section for actually transmitting write signal and supplying an electric power to the storage circuits of the display drive section, a column decoder section for selecting data lines for transmitting image signals; and a column selection switch section for transmitting the image signals to the data lines selected by the column decoder section. These are integrated and integrally formed on a semiconductor or insulating substrate (panel of the display device) thereby achieving space saving. Also, the exchange of signal is reduced by integrating all the elements over the panel, thereby achieving power reduction for the entire system including the display device.
Also, a display device according to the present invention can configure each of the current-driven luminescent elements by an organic EL element. In this display device, luminescent elements are configured by organic EL elements (OEL elements) having features of high-definition display, low-temperature process and so on.
Also, a display device according to the present invention includes a display drive section laid with a plurality of write lines, a plurality of data lines and power supply lines correspondingly disposed in an array pattern having a dot as a minimum unit of display, and having storage circuits for storing image signals when write signals are transmitted through the write lines and image signals are transmitted through the data lines and display control sections for supplying an electric current on the basis of the electric power supplied through the power supply lines to the liquid crystal drive sections on the basis of the image signals to effect tonal control using a liquid crystal, provided, as sets, with n sets in the same form in order for 2n tonal levels of representation within the dot array patterns. The display device further includes a row decoder section for selecting rows to transmit write signals to the write lines, a word line driver section for supplying an electric power for the storage circuits to hold storage and transmitting write signals to the write lines selected by the row decoder section, a column decoder for selecting the data lines, and a column selecting switch section for transmitting image signals as data signals for controlling display onto the data lines selected by column decoder section; integrated and integrally formed on a semiconductor or insulating substrate.
In this display device, there are provided a plurality of write lines and a plurality of data lines laid correspondingly to an array pattern having a dot as a minimum unit of display. Further, provided within the dot array pattern, n sets of storage circuits for storing image signals due to driving the write and data lines connected and display control sections for supplying an amount of current dependent on an electric power supplied to the liquid crystal driving sections. The invention additionally includes a display drive section provided within the dot array pattern, a row decoder section for selecting a row for transmitting a write signal to the write line, a word line driver section for actually transmitting write signal and supplying an electric power to the storage circuits of the display drive section, a column decoder section for selecting data lines for transmitting image signals, and a column selection switch section for transmitting the image signal to the data line selected by the column decoder section. These are integrated and integrally formed on a semiconductor or insulating substrate (panel of the display device) thereby achieving space saving. Also, the exchange of signal is reduced by integrating all the elements on the panel, thereby achieving power reduction for the system overall including the display device.
Also, a display device according to the invention configures the storage circuits by static circuits.
In this display device, in order to reduce data exchange and achieve power reduction, the storage circuits are configured by static circuits holding the image signals unless there is no change.
Also, in the storage circuit of the display device according to the invention, the static circuits are configured by latch circuits using CMOS clocked gates. In this display device, the storage circuits are configured by latch circuits using CMOS clocked gates (flip-flop), thereby achieving stable operation even with large variation in the TFTs.
Also, a display device according to the invention supplies electric power to each of the sets on the basis of xcex3-correction. In this display device, tonal representation can be effected on the dots by supplying electric power to each set depending on a relationship between a xcex3-correction brightness and an application voltage.
Also, a display device according to the invention further lays a plurality of read lines correspondingly to the dot array pattern to read out the image signals stored in the storage circuits when a read signal is transmitted. In this display device, a plurality of read lines are further laid correspondingly to the dot array pattern. When a read signal is transmitted, the image signals stored in the storage circuits are read out. Thus, the display device itself serves as a storage device for image signals (data).
Also, a display device according to the invention supplies power by controlling with an external power supply. In this display device, power is controlled by and supplied from the external power supply so that correction can be made on an each display-device basis for the variation in the relationship between a brightness and a supply power possibly caused in each display device due to the variation in manufacture.
Also, the word line driver section and the row decoder section of the display device according to the invention are correspondingly allocated to a length of the display drive section in a column direction while the column decoder section and the column selection switch section are correspondingly allocated to a length of the display drive section in a row direction. In this display device, in order to make the layout as small as possible in an area other than display, the word line driver section and the row decoder section are allocated correspondingly to a length of the display drive section in a column direction while the column line decoder section and the column selection switch section are allocated correspondingly to a length of the display drive section in a row direction, thereby achieving space saving.
Also, each column selection switch constituting the column selection switch section of the display device according to the invention is allocated correspondingly to a width of the dot array pattern. In this display device, in order to provide efficient layout, each column selection switch is allocated correspondingly to a width of the dot array pattern.
Also, a display device according to the invention has the row decoder section that selects a row for transmitting the write signal on the basis of an address signal representing the storage circuit to be stored with the image signal. In this display device, in order to enable selection of an arbitrary row, the row decoder section selects a row for transmitting the write signal on the basis of an address signal.
Also, the column decoder section of the display device according to the invention selects the data lines on the basis of the address signal. In this display device, in order to select arbitrary data lines (columns), the column decoder section transmits a data signal on the basis of an address signal.
Also, a display device according to the invention provides one pixel by three dots to develop and display red, blue and green as light source colors to input the image signals on a one-pixel basis, and the column decoder section selects data lines for storing the image signals in an amount of one pixel. In this display device, in color display one pixel is provided by three dots to develop and display red, blue and green to input the image signals on a one-pixel basis as a reference of display change, and the column decoder section selects data lines for storing the image signals in an amount of one pixel.
Also, the display device according to the invention provides one pixel by three dots to develop and display red, blue and green as light source colors to input the image signals on a plurality-of-pixel basis, and the column decoder section selects data lines for storing the image signals in an amount of a plurality of pixels. In this display device, when performing color display, image signals are inputted on a plurality-of pixels basis in order to lower the clock frequency used for storage, and the column decoder section selects data lines in an amount of plurality of pixels on the basis of the input.
Also, a display device according to the invention has an analog power control circuit for controlling power to be supplied to the power supply line further integrated and integrally formed on the substrate. In this display device, an analog power circuit for controlling the supply of power required for providing display is systematically, integrally formed on the same substrate.
Also, a display device according to the invention has at least a timing controller section for controlling timing for transmitting the address signal and a memory controller section for controlling transmission of the image signals further integrated and integrally formed on the substrate. In this display device, the timing controller section and the memory controller section are systematically, integrally formed on the same substrate.